Relief-piston for hig h-speed engines



(No Model.)-

J. E. SWEET. BELIEF PISTON FOR HIGH SPEED ENGINES.

No. 551,912. E -.X: J I

j x IIIIIIIII////IIIIIIIIIIIIIII/MIJI//W PATENT EEIoE.

JOHN E. SWEET, OF SYRACUSE, NEWV YORK.

RELIEF-PISTON FORHIGH-SPEED ENGINES.

SPECIFICATION forming part of Letters Patent No. 551,912, dated December24, 1895.

Serial No. 557,851. (No model.)

To all whom it may concern,-

Be it known that 1, JOHN E. SWEET, a citizen of the UnitedStates,residin g at Syracuse, in the county of Onondaga and State of NewYork, have invented certain new and useful Improvements inRelief-Pistons for High- Speed Engines; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake anduse the same.

My invention relates to improvements in relief devices for the cylindersof. high-speed engines; and it consists primarily in employing thecavity of the piston for that purpose and means therefor.

It is well known that from various causes water finds its way into thecylinders of engines. If in larger quantities than the clear ance in thecylinder will admit, a broken engine is the result, unless some means ofrelief is provided. In the slow-running slide-valve engines the valveitself lifts on its seat and thus permits the water to flow into thesteamchest. In high-speed engines with any form of valve the blow is toosudden for-the valve to afford the required relief, and in thepiston-valve engines and the like the valve cannot furnish that relief,however slow or however great the pressure. It is customary,nevertheless, to supply spring relief-valves of various designs tofurnish the proper relief to high-speed engines. These guard externalapertures opening from the cylinder into the engine-room; but all suchare defective, for the reason that their action is both too slow and tooinefi'icient for the high speeds now employed, since the valve-openingis necessarily limited in size and no valve can yield instantly under asmashing blow, and like all springuarded gateways, the valve 'isuncertain in its operation, which only occurs at irregular intervals.

My present invention consists primarily in utilizing the cavity of thepiston as the relief chamber, which I accomplish by opening aperturesinto the same guarded by tapered plugs forced into accurately-fittedseats under a determined pressure greater than the contemplated steam-pressure on the same area; also, in means for taking care of the plugsafter they are driven in by receiving them on tapered pins properlylocated for the purpose, where they stick fast until removed forreplacement, and, finally, in a novel means for signaling the engineerthat an accident has occurred, which consists in opening a communicationfrom the piston-cavity with the outer air by a hole drilledlongitudinally through the axis of the piston-rod meeting a hole drilledlaterally from the piston-cavity to said longitudinal aperture, thusforming a telltale-pathway for a small jet of steam.

Referring to the drawings forming a part of this specification, Figures1 and 2 illustrate different aspects of the piston in longitudinalmid-section, in which A is the pistonrod; B, the spider, O, thefollower; D, the bull-ring E E, piston-rings; F F, the reliefplugs; G G,the taper-pins for receiving the relief-plugs; g g, the tapered sockets,and H the hole in the piston-rod meeting the lateral hole it, makingcommunication with the cavity of the piston. Fig. 3 represents thepiston in horizontal section.

Like letters refer to like parts in the several figures.

The piston, except for the novel relief provisions, is of ordinaryconstruction and re quires but a brief passing description. The spider Bforms the front steam-face of the piston, into which the piston-rod A isfirmly fixed. The follower C forms the rear face of the piston and, inconjunction with the intermediate bull-ring D and the aforesaid spider,forms the cavity used as a relief-cavity. The piston-rings 0rpacking-rings E E are seated in annular channels between the bull-ringand the flanges on the spider and the follower respectively. The taperedapertures f are pierced in the front and rear walls of the piston-cavityrespectively, either or both, and tapered relief-plugs F are accuratelyfitted to said tapered apertures with steam-tight joints and so made asto require to be forced into place with a pressure so great that theywill not be loosened by any ordinary steampressure which will be broughtto bear on them, being intended to yield only to the violent impact orblow occasioned by the presence of a mass of water in theclearance-space too great to be disposed of through the ordinarychannels. These tapered plugs carry on their rear tapered sockets g,which are so proportioned and fitted as to engage with and stick fastupon tapered pins G located on the opposite wall of the cavity andprojecting toward the sockets. It is obvious that the pins may belocated on the relief-plugs and the sockets on the opposite wall inreversal of the plan shown in the drawings, this being the fullmechanical equivalent of the former construction. It is also obviousthat one or more tapered apertures and relief-plugs may be employed,according to the judgment and preference of the designer. In Fig. 1 Ihave shown the relief-plug F in its place in section, while in Fig. 2 Ihave shown the same forced from the seat and sticking on the pin Gprojecting from the opposite wall. In Fig. 2 also I show relief-plugsand apertures in both faces of the piston, one in place and the otherremoved.

The mode of operation is as follows: The tapered plugs having beenforced into place under great pressure are of course expected to remainin situ under all ordinary conditions, forming an impervious piston-facein no respect differing in action from the ordinary piston. When,however, water reaches the cylinder in quantities greaterthan providedfor by the clearance, the tapered relief-plu gs on that side are drivenin under the violent impact, thus anticipating breakage by yielding onpredetermined artificial breakage-lines thus provided, whereby theclearance is immediately increased by a volume equal to thepistoncavity, and the required relief furnished. The tapered plugs aretaken care of by the provision above referred to of tapered pins ortheir equivalent, situated immediately behind them, which catch audretain the plugs until replaced by means of the tapered sockets locatedupon the same at the rear.

The foregoing plan of relief does not compel the stopping of the enginewhen accidental flooding occurs, and the same may be allowed to rununtil stopping-time with no loss except the loss of steam due to theextra clearance. Should the flood of water continue to come in volumes,so as to force in the plugs on the other side, there is then an openingdirectly through the piston, and the engine of course stops, as is verydesirable. WVhen the engine is stopped, the plug or plugs should beforced back to place and the machinery restored to its normal condition.

By the provision of the alarm-hole drilled longitudinally through thepiston-rod to meet another hole extending to the piston-cavity abovereferred to a signal is instantly conveyed to the engineer by the escapeof steam at the outlet as soon as the cavity of the piston is brokeninto, while of course no steam enters the said cavity so long as theplugs remain in place. i

Among the advantages of this plan of relief may be mentioned thefollowing: First,the relief is instantaneous and sure to occur under thesudden violent impact of the unyielding mass of intruding water, savingthe parts from breakage under conditions where no springcontrolled valveof limited aperture could afford protection; second, the normalclearance, which is not excessive in the best e11- gines, is increasedto an amount sufficient to meet the emergency and take care of theinflow; third, no muss is made in the engineroom,the only indication ofaccident being the small jet of steam escaping from the pistonrod at thecross-head end, and, fourth, great simplicity and economy ofconstruction, there being no spring or working combination liable toderangement from long inactivity just at the critical times whenexpected to operate.

hat I claim as my invention, and desire to secure by Letters Patent, is

1. A steam engine cylinder containing a hollow piston provided on itssteam faces with relief apertures normally closed by plugs forciblyinserted therein under great pressure, but opening under impact todischarge surplus water in the cylinder into the hollow interior of thepiston, substantially as specified.

2. In a steam engine a cylinder containing a hollow piston normallyclosed on all sides but provided on its steam faces with predeterminedlines of breakage as described,whereby the said piston faces give way onthe said lines when encountering a mass of water in the clearance spaceunder high speed, thus enlarging clearance in the cylinder by admittingthe surplus water occupying the clearance space into the hollow interiorof the piston under impact, substantially as specified.

3. In a steam engine, a hollow piston having its steam faces perforatedand stopped with plugs forcibly inserted in the perforations, wherebythe piston remains entire under ordinary steam pressure, but yields atthe plugs under the impact of water in the cylinder beyond the clearancecapacity, thus admitting the surplus water to the cavity of the pistonthrough the said perforations, which serve the function of relief orescape valves, substantially as specified.

4. In a steam engine, a hollow piston having one or more taperedapertures in its steam faces, said apertures being normally closed byaccurately fitted tapered plugs forcibly inserted therein, substantiallyas specified.

5. In a steam engine, a hollow piston having one or more taperedapertures in its steam faces, said apertures being normally closed byaccurately fitted tapered plugs forcibly inserted therein, the saidplugs being provided with tapered sockets at the rear, in combinationwith tapered pins projecting from the opposite wall of the piston towardthe sockets, whereby when the plugs are forced in by the impact ofsurplus water in the cylinder they will be caught and retained on thepins, substantially as specified.

6. In a hollow relief piston such as described, the provision of taperedpins in combination with tapered sockets between the tapered reliefplugs and the opposite walls of 5 cylinder they are caught and retainedby the projecting member opposite, substantially as specified.

7. In a steam engine provided with a hollow relief piston having in itssteam faces re- I lief apertures normally closed by plugs forciblyinserted therein, but designed to yield under impact, an aperture oroutlet extending from the hollow interior of the piston into and alongthe axis of the piston rod to the I outer air, whereby when steam entersthe hollow interior of the said piston by the foreing of its Wall orface it may escape at the outlet and thus give Warning of its entry intothe interior of the piston, substantially as specified.

8. In a steam engine, a hollow piston pro- Vided with tapered aperturesin its steam faces, normally closed by accurately fitted tapered plugsforcibly inserted, having ta-.

pered sockets at their rear, stationary tapered pins located oppositethe tapered sockets, for receiving the same When the plugs are forcedin, and a tell tale outlet for steam from the piston cavity, extendingfrom the said cavity to the extremity of the piston rod near the crosshead, substantially as specified.

9. Ina holloW relief piston for high speed engines, such as described, atapered aperture f, tapered plug F accurately fitted to and forciblyseated in the said aperture, tapered socket g, tapered pin G locatedopposite the socket, and a tell tale outlet h, H, extending from thepiston cavity to the extremityv of the piston rod along the axis of thelatter, substantially as specified.

In testimony WhGI'GOfI afiix my signature in presence of two Witnesses.

JOHN E. SWEET.

Witnesses:

W. T. PoWERs, WM. F. KACEE.

